This is a low
tech calculator that can multiply and divide. Some action is needed to get a
result. For example, if you want to know how much 2 x 3 is, take the box with
the 2 squares on the left and move in a straight line to the right and take the
box with the 3 squares in the top and go down a straight line. The answer is on
the intersection point. You only have to count the squares ; ).

All this works without batteries ; ).

At the backside of this tessellations, folded from a 15 x 15 cm sheet / 32 grid, are several Fujimoto twists.